1. Field of the Invention
The invention relates to a communication light detector to visually checking the used/unused state of an optical transmission line by visualizing a communications light.
2. Description of the Related Art
In optical communication-related equipment, a used/unused state (hereinafter, referred to as “communication state”) is visually confirmed by visualizing communication light in an invisible light range to monitor steadiness of optical transmission line or to prevent man-caused erroneous removal of connector.
For visually confirming the communication state of the optical transmission line, a communication light detector to be removably attached to an adaptor having a light extraction hole (hereinafter, referred to as “communication light visualizing adaptor”) is used to detect whether or not the communication light is transmitted through the communication light visualizing adaptor based on the presence of leak light, which is an extracted portion of communication light transmitting through the communication light visualizing adaptor and is received through the light extraction hole, and then to output the communication state of the optical transmission line in the form allowing human to visually confirm it (see e.g. JP-A-2009-145676, JP-A-2010-231082, JP-A-2011-013359 and JP-A-2011-013360).